My opinion on the Paracorr: I had one for testing a few months ago. This was one of the
older units without an adjustable top. I find
just the reverse to be true (from a previous replier who stated there was no difference using
naglers but perhaps cheaper eyepieces would benefit). I found no difference using , lets say,
less expensive eyepieces- some of which perform
fairly well without the ParaCorr but showed no
detectable improvement using it. The specific
Nagler that I tried with it was the 22mm type 4
which showed quite a significant improvement in
performance on my F/4.5, even though Tele-Vue says this old style is not optimized for this new
design. I will say that the apparent improvement
decreases with increasingly powerful eyepieces ie:
the 7mm Nagler barely shows any improvement. Perhaps this is what the other reply was making reference to and was not aware of the effect using
the 'Big' Naglers.
P.S. : I am waiting for the new 'improved' ParaCorr to come out. It is supposed to have larger elements and be targeted for unvignetted(hopefully) viewing with the lowest power eyepieces such as the 35mm Panoptic and the 31mm Nagler. I want to see what it will do for my 30mm
WideScan II.
Herb